Combinatorial metabolic engineering of industrial Gluconobacter oxydans DSM2343 for boosting 5-keto-D-gluconic acid accumulation. Issue 1 (December 2016)

• Record Type: Journal Article
• Authors: Yuan, Jianfeng; Wu, Mianbin; Lin, Jianping; Yang, Lirong
• Is Part Of: BMC biotechnology. Volume 16:Issue 1(2016)
• Page Start: 1
• Page End: 14
• Publication Date: 2016-12
• Subjects: 5-keto-D-gluconate -- L-(+)-tartaric acid -- Pyrroloquinoline quinone -- Respiratory chain -- Fed-batch fermentation; Biotechnology -- Periodicals; 660.605
• DOI: 10.1186/s12896-016-0272-y
• Languages: English
• ISSNs: 1472-6750

Abstract

Abstract Background L-(+)-tartaric acid (L-TA) is an important organic acid, which is produced from the cream of tartar or stereospecific hydrolysis of thecis -epoxysuccinate. The former method is limited by the availability of raw material and the latter is dependent on the petrochemical material. Thus, new processes for the economical preparation of L-TA from carbohydrate or renewable resource would be much more attractive. Production of 5-keto-D-gluconate (5-KGA) from glucose byGluconobacter oxydans is the first step to produce L-TA. The aim of this work is to enhance 5-KGA accumulation using combinatorial metabolic engineering strategies inG. oxydans . ThesldAB gene, encoding sorbitol dehydrogenase, was overexpressed in an industrial strainG. oxydans ZJU2 under a carefully selected promoter, P0169 . To enhance the efficiency of the oxidation bysldAB, the coenzyme pyrroloquinoline quinone (PQQ) and respiratory chain were engineered. Besides, the role insldAB overexpression, coenzyme and respiratory chain engineering and their subsequent effects on 5-KGA production were investigated. Results An efficient, stable recombinant strain was constructed, whereas the 5-KGA production could be enhanced. By self-overexpressing thesldAB gene inG. oxydans ZJU2 under the constitutive promoter P0169, the resulting strain, G. oxydans ZJU3, produced 122.48 ± 0.41 g/L of 5-KGA. Furthermore, through the coenzyme and respiratory chain engineering, the titer and productivity of 5-KGA reached 144.52 ± 2.94 g/L and 2.26 g/(L · h), respectively, in a 15 L fermenter. It could be further improved the 5-KGA titer by 12.10 % through the fed-batch fermentation under the pH shift and dissolved oxygen tension (DOT) control condition, obtained 162 ± 2.12 g/L with the productivity of 2.53 g/(L · h) within 64 h. Conclusions The 5-KGA production could be significantly enhanced with the combinatorial metabolic engineering strategy inGluconobacter strain, includingsldAB overexpression, coenzyme and respiratory chain engineering. Fed-batch fermentation could further enlarge the positive effect and increase the 5-KGA production. All of these demonstrated that the robust recombinant strain can efficiently produce 5-KGA in larger scale to fulfill the industrial production of L-TA from 5-KGA.